Production process of high-purity 2-imidazolinone

Abstract

The invention discloses a production process of high-purity 2-imidazolinone, which comprises the following steps: adding softened water, a catalyst, raw materials urea and ethidene diamine into a reaction kettle, vacuumizing, filling nitrogen, reacting for a period of time at a certain pressure and temperature, and continuously reacting for a period of time at a certain vacuum degree and temperature; after the reaction is finished, cooling reaction liquid, carrying out primary dissolution with ethanol, filtering, evaporating filtrate obtained by filtering out solid impurities to recover ethanol, carrying out secondary dissolution with ethanol on a material obtained by evaporation, filtering, heating, carrying out cooling crystallization, and drying to obtain a finished product 2-imidazolinone; and continuously recycling the centrifugate. The one-way yield of the 2-imidazolinone prepared by the method is more than 90% and exceeds that of the existing production process.

Description

Technical Field

[0001] The invention belongs to the technical field of fine chemical product production, and particularly relates to a production process of high-purity 2-imidazolidinone. Background Art

[0002] 2-Imidazolidinone, also known as ethyleneurea, ethyleneurea, and 2-imidazolidinone, is used as a formaldehyde capture agent, a formaldehyde removal agent, and can be added to metals as a corrosion inhibitor to inhibit metal corrosion. It is also a key starting material for synthesizing 2-imidazolidinone derivatives such as N-chloroformyl-2-imidazolidinone, 1-chloroformyl-3-acetyl-2-imidazolidinone, 1-chloroformyl-3-methylsulfonyl-2-imidazolidinone, N-hydroxyethyl-2-imidazolidinone, 1-methylsulfonyl-2-imidazolidinone, 1,3-dimethyl-2-imidazolidinone, and 1-acetyl-2-imidazolidinone. It is used in many fields such as organic synthesis, functional materials, medicine, synthetic agricultural chemicals, manufacturing resins, plasticizers, spray paints, adhesives, etc. It is a fine chemical with broad market prospects.

[0003] Literature reports that the synthesis methods of 2-imidazolidinone can be divided into the following types according to the starting materials: urea method, carbonate method, carbon oxide (CO, CO2) method, ammonium carbonate method and phosgene method. Although the urea method has problems such as high requirements for temperature control and low yield, considering the raw material source, production cost, and practicality of process technology, the production of 2-imidazolidinone by urea method still has good research value and application prospects.

[0004] The existing technology for synthesizing 2-imidazolidinone using ethylenediamine and urea as main raw materials is analyzed as follows: (1) Only ethylenediamine and urea are used for preparation. Chinese patent CN102030711B discloses the following process: only ethylenediamine and urea are used for heating and reacting until the generation of ammonia is significantly reduced or stopped, and the excess ethylenediamine is recovered and the obtained condensation mixture is evaporated and collected to obtain 2-imidazolidinone, which is then refined using ethanol; the reaction temperature of this scheme reaches 260°C, the single-pass yield is about 90%, and the product purity is about 95% on average. Ma Weilin et al. published a paper entitled "A New Process for Synthesis of 2-Imidazolidinone" in "Pesticides" No. 3, 1986, selecting ethylenediamine and urea to react at normal pressure, and adopting two-stage heating and controlling the reflux ratio during the reaction process, and obtained relatively satisfactory results, but the yield and purity were both low. (2) Using ethylenediamine and urea as raw materials, and using water and ethylene glycol as solvents for preparation, Chinese patent CN115160230A, Chinese patent CN 106831593 A, Yao Zhuanle et al. published a paper entitled "Preparation of 1,3-dimethyl-2-imidazolidinone" in "Applied Chemical Industry" No. 09, 2009, and Wu Kai et al. published a paper entitled "Effect of Solvent on Synthesis of 2-Imidazolidinone" in "Fine and Specialty Chemicals" No. 11, 2010, and proposed similar or similar production methods; Chinese patent CN 107903214 A adds dimethylformamide to the reaction system based on the mixture of ethylene glycol and water. The above documents all have the following problems to varying degrees: high reaction temperature (reaction temperature as high as 220-260°C), long reaction time (some require 5-6 hours for heat preservation reaction), polymer impurities are precipitated in a solid suspension state after adding solvent to the reaction liquid, and it is necessary to filter repeatedly to separate the impurities, and some need to add activated carbon for decolorization, low product yield (no more than 90%), and low product purity (generally below 99%). (3), using ethylenediamine and urea as raw materials and only using water as solvent for preparation, Zhang Qihua published a paper entitled "Synthesis of Ethylene Urea and the Effect of Water" in "Ningxia Chemical Industry" No. 2, 1994. Water was added before the reaction of urea and ethylenediamine, and the reaction was carried out at 240-250°C for 8 hours. The reaction product was recrystallized with chloroform, and the yield was 98.4%, but the product purity was not given. Experiments without adding water were also conducted, but the target product was not obtained; Chinese patent CN1739821 discloses the following synthesis process: urea and ethylenediamine are added in proportion to a reactor, water is added, heated and melted, stirred, heated to react to form a white viscous substance, and then heated to melt the white solid, cooled, added water to dissolve, heated to hydrolyze, cooled again, filtered, crystallized, filtered again, and dried to obtain white crystals as the finished product. The process reaction temperature is 230°C, and no specific reaction time is given. Although the reaction product is post-treated with water and white crystals are obtained, the product quality index and yield are not provided.(4) Using ethylenediamine and urea as raw materials and 2-imidazolidinone as solvent, Hu Xia studied the technical scheme of synthesizing 2-imidazolidinone using 2-imidazolidinone as a high boiling point solvent, urea and ethylenediamine as raw materials, and water as a catalyst in her master's thesis "Improvement of the Synthesis Process of 2-Imidazolidinone and Its Derivatives" (2016) at Ningxia University. However, under the optimal process, adding 2-imidazolidinone of the same mass as urea as a reaction solvent before heating requires heating to 160°C for 2 hours (the insulation time is not clearly specified), the product yield does not exceed 91%, and the product purity does not exceed 99%. The operation is cumbersome and it is difficult to achieve industrial production.

[0005] As the usage of 2-imidazolidinone and its subsequent products in many industries such as medicine, pesticides, optoelectronic materials, and special-purpose cables has increased, the quality index requirements for 2-imidazolidinone have been significantly improved, especially 2-imidazolidinone with higher purity has become a hot spot for research and attention of scientific researchers. To this end, in-depth research on the synthesis and purification process of 2-imidazolidinone, improving product quality and yield, meeting the use requirements of high-end users, and improving product economic benefits also play an important practical role in promoting the development of the industry. This research topic has important social and economic significance. Summary of the invention

[0006] In order to solve the deficiencies of the prior art, the present invention proposes a production process of high-purity 2-imidazolidinone, comprising: using urea and ethylenediamine as raw materials, in the presence of a catalyst and water, performing a two-step reaction of low-pressure reaction and vacuum reaction, and after the reaction is completed, cooling the reaction liquid and performing post-treatment; the catalyst is a combination of triethylmethylammonium chloride, sulfonamide acid and sodium m-nitrobenzene sulfonate; the vacuum degree of the low-pressure reaction is 0.3-0.4MPa, and the reaction temperature is 140-150°C; the vacuum degree of the vacuum reaction is 0.06-0.08MPa, and the reaction temperature is 155-165°C.

[0007] In the embodiment of the present invention, the post-processing step includes filtering and evaporating ethanol; further, the post-processing step also includes adding ethanol for secondary dissolution, followed by secondary cooling, crystallization, centrifugation and drying.

[0008] Preferably, the molar ratio of urea (100%), ethylenediamine (100%) and water is 1:1.03-1.09:1.68-1.85. The method greatly reduces the input amount of ethylenediamine.

[0009] Preferably, the amount of triethylmethylammonium chloride added is 0.13%-0.22% of the mass of urea.

[0010] Preferably, the amount of sulfonamide acid added is 0.05%-0.25% of the mass of urea.

[0011] Preferably, the amount of sodium m-nitrobenzene sulfonate added is 0.16%-0.25% of the mass of urea.

[0012] In the technical scheme provided by the present invention, softened water, a catalyst, raw material urea and ethylenediamine are added into a reaction kettle, vacuumed and then filled with nitrogen, reacted for a period of time at a certain pressure and temperature, and then continued to react for a period of time at a certain vacuum degree and temperature; after the reaction is completed, the reaction liquid is cooled, dissolved with ethanol once, filtered, the filtrate obtained by filtering out solid impurities is evaporated to recover ethanol, the evaporated material is dissolved with ethanol twice, filtered, heated, cooled and crystallized, and dried to obtain a finished product 2-imidazolidinone; and the centrifuged liquid is continuously reused.

[0013] Preferably, the production process comprises the following steps:

[0014] S1. Cyclization reaction:

[0015] Add the measured water, catalyst, urea and ethylenediamine to the reactor in sequence, seal it, turn on the vacuum pump, and when the vacuum degree of the reactor reaches 0.04-0.06MPa, maintain it for 10-20 minutes, turn off the vacuum pump, turn on the agitator, and fill the reactor with nitrogen. When the pressure in the reactor reaches 0.3-0.4MPa, stop the nitrogen introduction;

[0016] Pass the heating medium into the jacket of the reactor, raise the temperature to 140-150°C within 30-40 minutes, and maintain this temperature for 1-1.5 hours;

[0017] Close the heating medium inlet valve, slowly open the reactor vent valve, discharge the gas into the ammonia absorption tank, and when the pressure in the reactor drops to normal pressure (the pressure gauge shows 0), turn on the vacuum pump. When the vacuum degree in the reactor reaches 0.06-0.08MPa, open the heating medium inlet valve, raise the temperature to 155-165℃ within 40-50 minutes, and maintain at this temperature for 2-2.5 hours.

[0018] Further, post-processing includes:

[0019] Under vacuum conditions, close the heating medium inlet valve, release the heating medium in the jacket, and then introduce cooling medium into the jacket of the reactor to start cooling;

[0020] When the kettle temperature is about to drop below 80°C, add 95% ethanol along the inner wall of the kettle and continue stirring for 1-2 hours;

[0021] Furthermore, post-processing also includes:

[0022] S2, filtration, evaporation of ethanol:

[0023] After the material with 95% ethanol is added and stirred, compressed air is used to press the material from the discharge port of the reactor into the evaporator through the pipeline filter installed on the pipeline connected to the evaporator to filter out solid matter and mechanical impurities;

[0024] Steam is introduced into the jacket of the evaporator to start heating, and the ethanol obtained by evaporation is continuously reused. When white solid material is observed at the bottom of the evaporator and the gas phase temperature exceeds 78°C and shows a trend of continuing to rise, the steam valve is immediately closed;

[0025] S3, secondary dissolution, cooling, crystallization:

[0026] Add cooling water to the jacket of the evaporator. When the temperature of the material in the evaporator drops below 90°C, add the measured 95% ethanol along the inner wall of the evaporator. Start stirring (to prevent the stirring motor from burning) to ensure that the stirrer starts and runs normally. Heat the evaporator. When the temperature of the material in the evaporator reaches 65-70°C, continue stirring for 20-40 minutes. Use compressed air to press the material from the discharge port of the evaporator into the crystallization kettle through the pipe filter installed on the pipe connected to the crystallization kettle;

[0027] Slowly introduce chilled brine into the jacket of the crystallization kettle and cool it down to below 5°C at a rate of 5-10°C / 5 minutes. When the temperature of the crystallization kettle reaches 20-25°C, add a small amount of 2-imidazolidinone seed crystals into the crystallization kettle;

[0028] S4, centrifugation, drying:

[0029] The timer starts from the time when the temperature of the crystallization kettle drops below 5°C. After 20-30 minutes, the material in the crystallization kettle is placed in a centrifuge for centrifugation, and the solid material is sent to a disc dryer for drying; the centrifuge liquid is reused.

[0030] Preferably, in the post-treatment step, 95% ethanol is added twice, and the mass ratio of ethanol to urea is 1:

[0031] (5.3-6.0).

[0032] The existing process for preparing 2-imidazolidinone using ethylenediamine and urea as raw materials, whether using water and ethylene glycol as a mixed solvent, using water alone as a solvent, or using 2-imidazolidinone as a solvent (also adding water), has the following main problems: (1) During the synthesis reaction, the amount of ethylenediamine is too large, generally exceeding 40% of the theoretical ratio. During the reaction, the excess ethylenediamine will cause multiple side reactions and generate complex high melting point compounds. In addition, the ethylenediamine needs to be recovered after the reaction is completed, which increases the operation steps; (2) It is technically difficult to completely remove the solvent ethylene glycol used in the synthesis from the finished product in the subsequent processing steps, and it is necessary to use other solvents for multiple recrystallizations, which virtually reduces the product yield; (3) The reaction temperature is too high. The reaction temperature provided by different literature processes is too high. The reaction temperature varies from 150 to 160°C, from 180 to 220°C, and even from 230 to 260°C. High reaction temperature inevitably leads to more side reactions and more by-products, which increases the difficulty of subsequent purification of the product. (4) The reaction time is long. Regardless of the reaction temperature range, the reaction time alone, excluding the heating time, exceeds 4 hours. (5) The post-processing of the reaction materials, including the recrystallization process, has technical defects to varying degrees, resulting in low product purity, generally less than 99.3%. The product yield is low, and the product yield obtained in laboratory operations is less than 99%. (6) The solvent unit consumption and energy consumption used in the post-processing are high, resulting in high cost of high-purity products that cannot compete with similar foreign products. The invention uses the basic theory of organic synthesis and the basic theory of catalysis, fully analyzes the reaction mechanism of ethylenediamine and urea, takes ethylenediamine and urea as raw materials, takes softened water as solvent, uses triethylmethylammonium chloride, sulfonamide acid and sodium m-nitrobenzenesulfonate as catalysts, and through two reaction steps of low-pressure reaction and vacuum reaction, reduces the reaction temperature, strengthens the post-treatment of the reaction liquid, especially recrystallization and mother liquor reuse, and other optimal process selections, systematically and comprehensively studies the preparation process of 2-imidazolidinone, and forms a production process with higher purity and higher yield.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. Regarding the use of solvents, the present invention only uses demineralized water as a solvent, while most of the existing public synthesis processes use water and ethylene glycol as two components as solvents, or use dimethylamide as a solvent at the same time, or use 2-imidazolidinone as a solvent;

[0035] 2. Regarding the use of catalysts, the present invention proposes for the first time the use of triethylmethylammonium chloride, sulfonamide acid, and sodium m-nitrobenzenesulfonate as catalysts, thereby increasing the product yield, reducing the reaction temperature, and shortening the reaction time;

[0036] 3. Regarding the adjustment of reaction pressure and temperature, the present invention realizes a 2-imidazolidinone synthesis process with improved yield through two reaction steps of low-pressure reaction and vacuum reaction. Compared with the existing process, the reaction temperature is reduced by 50 to 90° C. (the reaction temperature in some public documents is even as high as 260° C.), the reaction time is shortened by 3 to 5 hours, the molar ratio of ethylenediamine and urea is close to the theoretical value, the side reactions are reduced, and the amount of by-products generated is reduced;

[0037] 4. The reaction temperature is lowered to solve the problem of material adhering to the kettle wall. The existing production process adopts a normal pressure high temperature synthesis process (the reaction temperature is controlled at 160-260°C), and solid materials are generated during the reaction process, which inevitably leads to problems such as high local temperature, coking of materials or a small amount of hardening. When the present invention performs the cyclization reaction, reasonable operating pressure and temperature are selected, especially in the vacuum reaction stage, the dual stirring effects of mechanical stirring of the agitator and vacuum extraction, and water is used as a solvent. When water vaporizes and evaporates, micropores are generated in the material, which helps to disperse the material and will not form a "tightly clumping" state. The reaction materials will not agglomerate in local areas in the reactor, avoiding or reducing the adhesion of materials to the kettle wall (materials adhering to the reactor wall for a long time will lead to poor reaction effect of raw materials). In this way, insufficient contact of the reaction materials is avoided to a certain extent, and local overheating of the material or even coking and carbonization phenomena are eliminated, resulting in incomplete or even reaction failure, increased side reactions, difficult post-processing, decreased yield, black spots in the product and a series of subsequent problems;

[0038] 5. The present invention has good reaction effect and reduced side reactions, and the amount of by-products, especially the amount of complex high-viscosity and high-melting-point polymers, is greatly reduced. Impurities insoluble in ethanol are filtered out, and a small pipeline filter is used to replace the existing precision filter that occupies a large space, which saves equipment installation space, has a compact device layout, reduces leakage points, improves production safety, and makes impurity cleaning more convenient;

[0039] 6. Regarding the post-treatment of the cyclization reaction liquid, most of the existing processes use ethanol to wash twice and dry; or dissolve and filter with ethanol for the first time, evaporate the filtrate and then rinse the solid with ethanol twice, and then dry it. The product obtained in this way has low purity, unstable quality, and large differences in quality indicators between batches;

[0040] 7. The present invention determines the best process for the cyclization reaction. Due to the lower reaction temperature and the shorter reaction time, the side reactions are reduced and the amount of by-products generated is also reduced. After the ethanol recovered by dissolving once with ethanol and the mother liquor produced by ethanol recrystallization are used for five times in industrial production, the product purity still reaches 99.16% and the yield is 98.87%. In this way, the unit consumption of ethanol is significantly reduced, the production cost is reduced, and the economic benefit is improved; 8. The 2-imidazolidinone prepared by the present invention has a single-pass yield of more than 90%, which exceeds the existing production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0042] Figure 1 The present invention provides a process flow chart of the production process.

[0043] Figure 2 This is the chromatogram for detecting the product of Example 5.

[0044] Figure 3 This is the chromatogram of the product test of Comparative Example 2. DETAILED DESCRIPTION

[0045] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0046] The present invention provides a production process of high-purity 2-imidazolidinone, comprising the following steps: adding softened water, a catalyst, raw material urea and ethylenediamine into a reaction kettle, first evacuating and then filling with nitrogen, then reacting for a period of time at a certain pressure and temperature, and then continuing to react for a period of time at a certain vacuum degree and temperature. After the reaction is completed, the reaction liquid is cooled, dissolved with ethanol once, filtered, the filtrate obtained by filtering out solid impurities is evaporated to recover ethanol, the evaporated material is dissolved with ethanol twice, filtered, heated, cooled and crystallized, and dried to obtain the finished product 2-imidazolidinone; the centrifuged liquid is continuously reused.

[0047] In an embodiment of the present invention, the reactor is provided with an agitator, which is connected to a vacuum pump and a nitrogen source respectively, and the vacuum degree in the reactor is controlled and nitrogen is introduced into the reactor respectively. The reactor is provided with a jacket, and the temperature of the reactor is adjusted by a heating medium or a cooling medium. A heating medium inlet valve is provided on the pipeline connected to the jacket of the reactor, and a steam valve is one of the heating medium inlet valves; the discharge port of the reactor is also connected to the evaporator, and a pipeline filter is provided on the connecting pipeline; the reactor is also connected to the ammonia absorption tank through a pipeline with a reactor vent valve. The evaporator is connected to the crystallization kettle through a pipeline, and a pipeline filter is provided on the connecting pipeline; this is a commonly used equipment and structure in the chemical industry, and will not be described in detail here.

[0048] In the embodiment of the present invention, the following process steps are provided:

[0049] 1. Cyclization reaction

[0050] Add the measured softened water, catalyst, urea and ethylenediamine to the reactor in sequence, seal it, turn on the vacuum pump connected to the reactor, when the vacuum degree of the reactor reaches 0.04-0.06MPa, maintain it for 10-20 minutes, turn off the vacuum pump, turn on the agitator, fill the reactor with nitrogen, and stop the nitrogen introduction when the pressure in the reactor reaches 0.3-0.4MPa;

[0051] Pass the heating medium into the jacket of the reactor, raise the temperature to 140-150°C within 30-40 minutes, and maintain this temperature for 1-1.5 hours;

[0052] Close the heating medium inlet valve, slowly open the reactor vent valve, discharge the gas to the ammonia absorption tank, and when the pressure in the reactor drops to normal pressure (the pressure gauge shows 0), turn on the vacuum pump. When the vacuum degree in the reactor reaches 0.06-0.08MPa, open the heating medium inlet valve, raise the temperature to 155-165℃ within 40-50 minutes, and maintain at this temperature for 2-2.5 hours;

[0053] Close the heating medium inlet valve under vacuum conditions, release the heating medium in the jacket, and then introduce cooling medium into the reactor jacket. Start cooling;

[0054] When the kettle temperature is about to fall below 80°C, add 95% ethanol along the inner wall of the kettle and continue stirring for 1-2 hours. In the low-pressure reaction stage, nitrogen is charged into the reaction system to increase the pressure. The reaction of urea and ethylenediamine is carried out in a nearly homogeneous state. Combined with the catalytic effect of the catalyst, part of the ammonia (NH3) molecules, water and nitrogen generated by the reaction coexist in the gas phase, which accelerates the escape of ammonia (NH3) molecules in the urea molecules and increases the speed of the cyclization reaction. Under the protection of nitrogen, the oxidation, decomposition and other side reactions of the raw materials and intermediate transition products are avoided;

[0055] In the vacuum reaction stage, compared with the low-pressure reaction process, the reaction temperature is relatively increased, the reaction rate of unreacted raw materials and transition intermediates is accelerated under vacuum conditions, and the ammonia (NH3) molecules generated by the reaction are quickly extracted from the reaction system. According to the principle of chemical reaction equilibrium, the reaction rate in the direction of the product 2-imidazolidinone is accelerated.

[0056] 2. Filtration and evaporation of ethanol

[0057] After the material with 95% ethanol is added and stirred, compressed air is used to press the material from the discharge port of the reactor into the evaporator through the pipeline filter installed on the pipeline connected to the evaporator to filter out solid matter and mechanical impurities;

[0058] Steam is introduced into the jacket of the evaporator to start heating, and the ethanol obtained by evaporation is continuously reused. Once white solid material is observed at the bottom of the evaporator and the gas phase temperature exceeds 78°C and shows a trend of continuing to rise, the steam valve is immediately closed.

[0059] 3. Secondary dissolution, cooling and crystallization

[0060] Cooling water is introduced into the jacket of the evaporator. When the temperature of the material in the evaporator drops below 90°C, the measured 95% ethanol is added along the inner wall of the evaporator. The stirring is started by jogging (to prevent the stirring motor from burning). Ensure that the stirrer starts and runs normally. Heat the evaporator. When the temperature of the material in the evaporator reaches 65-70°C, the stirring is continued for 20-40 minutes. Use compressed air to press the material from the discharge port of the evaporator into the crystallization kettle through the pipeline filter installed on the pipeline connected to the crystallization kettle.

[0061] Slowly introduce chilled brine into the jacket of the crystallization kettle and cool it down to below 5°C at a rate of 5-10°C / 5 minutes. When the temperature of the crystallization kettle reaches 20-25°C, add a small amount of 2-imidazolidinone seed crystals into the crystallization kettle.

[0062] 4. Centrifugation and drying

[0063] The timer starts from the time when the temperature of the crystallization kettle drops below 5°C. After 20-30 minutes, the material in the crystallization kettle is placed in a centrifuge for centrifugation, and the solid material is sent to a disc dryer for drying; the centrifuge liquid is reused.

[0064] The invention adopts ethanol to dissolve the ring-closure reaction liquid twice, wherein the ring-closure reaction liquid is dissolved with ethanol for the first time, then filtered and impurities are removed, and the solid-containing material obtained by evaporating the ethanol from the material dissolved with ethanol for the first time is dissolved with ethanol for the second time, and the dissolution temperature is lower than the boiling point of ethanol in the second dissolution of 2-imidazolidinone. 2-imidazole is dissolved under the selected temperature condition, and a certain amount of ethanol is maintained to evaporate (recycle) while dissolving. The characteristic that 2-imidazolidinone has a large solubility in hot ethanol is utilized, and a reasonable ethanol feed amount is added to ensure that the 2-imidazolidinone dissolved in ethanol has reached or is close to saturation at the end of the second dissolution operation, and the 2-imidazolidinone precipitation speed is fast and the crystal form is good in the subsequent cooling crystallization process.

[0065] Unless otherwise specified, % in this application document refers to wt%.

[0066] 1. Main quality requirements of raw materials

[0067] Ethylenediamine, content ≥98%;

[0068] Urea complies with GB 2440-2001;

[0069] Softened water specific resistance ≥2×10 5 ohm;

[0070] 95% industrial ethanol, in accordance with GB 6820-1992;

[0071] 2. Material ratio

[0072] The molar ratio of urea (100%), ethylenediamine (100%) and water is 1: (1.03-1.09): 1.68-1.85

[0073] 95% industrial ethanol is added twice, and the mass ratio of its dosage to urea is 1:(5.3-6.0) The amount of triethylmethylammonium chloride added is 0.13%-0.22% of the mass of urea;

[0074] The amount of sulfonamide acid added is 0.05%-0.25% of the urea mass;

[0075] The amount of sodium m-nitrobenzene sulfonate added is 0.16%-0.25% of the urea mass.

[0076] The detection method adopts high performance liquid chromatography, and the chromatographic conditions are:

[0077] 1. Instruments:

[0078] Liquid chromatograph, infusion pump (flow range 0.1mL / min~5.0mL / min), within this range its flow stability is ±1%; detector, UV detector; chromatographic column: stationary phase is C18, particle size 5μm, length is 250mm, inner diameter is 4.6mm stainless steel column; chromatographic workstation or integrator; injector: micro injector; quantitative injection tube, 10μL; matching filter; ultrasonic cleaner.

[0079] 2. Chromatographic analysis conditions:

[0080] Mobile phase, acetonitrile: water = 60:40 (volume ratio), wherein acetonitrile is chromatographically pure; water is ultrapure water or freshly distilled water, filtered through a 0.45 μm organic filter membrane; flow rate, 1.0 mL / min; wavelength, 210 nm; column temperature: 30 ° C; injection volume: 10 μL.

[0081] Example 1

[0082] 1. Cyclization reaction

[0083] 51Kg of softened water, 0.15Kg of three catalysts triethylmethylammonium chloride, 0.05Kg of sulfonamide acid, 0.1Kg of sodium m-nitrobenzenesulfonate, 100Kg of urea and 104Kg of ethylenediamine were added into the reactor in sequence, and the mixture was sealed. The vacuum pump was turned on. When the vacuum degree of the reactor reached 0.04MPa, the mixture was maintained for 20 to 1 minute. The vacuum pump was turned off. A stirrer was turned on and nitrogen was charged into the reactor. When the pressure inside the reactor reached 0.3MPa, nitrogen was stopped from entering.

[0084] A heating medium was introduced into the jacket of the reactor, and the temperature was raised to 140°C within 40 minutes, and maintained at this temperature for 1.5 hours;

[0085] Close the heating medium inlet valve, slowly open the reactor vent valve, discharge the gas to the ammonia absorption tank, and when the pressure in the reactor drops to normal pressure (the pressure gauge shows 0), turn on the vacuum pump. When the vacuum degree in the reactor reaches 0.06MPa, open the heating medium inlet valve and raise the temperature to 165°C within 50 minutes, and keep it at this temperature for 2 hours;

[0086] Close the heating medium inlet valve under vacuum conditions, release the heating medium in the jacket, and then introduce cooling medium into the reactor jacket. Start cooling;

[0087] When the kettle temperature is about to drop below 90°C, 320 kg of 95% ethanol is metered into the kettle along the inner wall, and stirring is continued for 1-2 hours.

[0088] 2. Filtration and evaporation of ethanol

[0089] After the stirring of the material with 95% ethanol is completed, the material is pressed from the reactor into the evaporator with compressed air to filter out the solid matter and mechanical impurities therein;

[0090] Steam is introduced into the jacket of the evaporator to start heating, and the ethanol obtained by evaporation is continuously reused. Once white solid material is observed at the bottom of the evaporator and the gas phase temperature exceeds 78°C and shows a trend of continuing to rise, the steam valve is immediately closed.

[0091] 3. Secondary dissolution, cooling and crystallization

[0092] Cooling water is introduced into the jacket of the evaporator. When the temperature of the material in the evaporator drops below 90°C, 230 kg of 95% ethanol is added along the inner wall of the evaporator. The stirring is started by jogging (to prevent the stirring motor from being burned). Ensure that the stirrer starts and runs normally. Heat the evaporator. When the temperature of the material in the evaporator reaches 65°C, the stirring is continued for 30 minutes. The material is pressed from the evaporator into the crystallization kettle with compressed air.

[0093] Slowly introduce chilled brine into the jacket of the crystallization kettle and cool it down to below 5°C at a rate of 5-10°C / 5 minutes. When the temperature of the crystallization kettle reaches 25°C, add a small amount of 2-imidazolidinone seed crystals into the crystallization kettle.

[0094] 4. Centrifugation and drying

[0095] The timing starts from when the temperature of the crystallization kettle drops below 5°C. After 20 minutes, the materials in the crystallization kettle are placed in a centrifuge for centrifugation. The centrifugal liquid is recycled and the solid materials are sent to a disc dryer for drying to obtain 132.01 kg of white crystals. The melting point of the product is analyzed to be 131.5°C, the product content is 99.27%, and the calculated product yield is 92.35%.

[0096] Example 2

[0097] 1. Cyclization reaction

[0098] 53Kg of softened water, 0.16Kg of catalyst triethylmethylammonium chloride, 0.1Kg of sulfonamide acid, 0.2Kg of sodium m-nitrobenzenesulfonate, 100Kg of urea and 105Kg of ethylenediamine were added to the reactor in sequence, and the mixture was sealed. The vacuum pump was turned on. When the vacuum degree of the reactor reached 0.04MPa, the reactor was maintained for 10 minutes. The vacuum pump was turned off. A stirrer was turned on and nitrogen was charged into the reactor. When the pressure in the reactor reached 0.35MPa, nitrogen was stopped from being introduced.

[0099] A heating medium was introduced into the jacket of the reactor, and the temperature was raised to 150°C within 35 minutes, and maintained at this temperature for 1.5 hours;

[0100] Close the heating medium inlet valve, slowly open the reactor vent valve, discharge the gas to the ammonia absorption tank, and when the pressure in the reactor drops to normal pressure (the pressure gauge shows 0), turn on the vacuum pump. When the vacuum degree in the reactor reaches 0.06MPa, open the heating medium inlet valve, raise the temperature to 160℃ within 50 minutes, and maintain at this temperature for 2 hours;

[0101] Close the heating medium inlet valve under vacuum conditions, release the heating medium in the jacket, and then introduce cooling medium into the reactor jacket. Start cooling;

[0102] When the kettle temperature is about to drop below 90°C, 330 kg of 95% ethanol is metered into the kettle along the inner wall, and stirring is continued for 1.2 hours.

[0103] 2. Filtration and evaporation of ethanol

[0104] After the stirring of the material with 95% ethanol is completed, the material is pressed from the reactor into the evaporator with compressed air to filter out the solid matter and mechanical impurities therein;

[0105] Steam is introduced into the jacket of the evaporator to start heating, and the ethanol obtained by evaporation is continuously reused. Once white solid material is observed at the bottom of the evaporator and the gas phase temperature exceeds 78°C and shows a trend of continuing to rise, the steam valve is immediately closed.

[0106] 3. Secondary dissolution, cooling and crystallization

[0107] Cooling water is introduced into the jacket of the evaporator. When the temperature of the material in the evaporator drops below 90°C, 240 kg of 95% ethanol is added along the inner wall of the evaporator. The stirring is started by jogging (to prevent the stirring motor from being burned). Ensure that the stirrer starts and runs normally. Heat the evaporator. When the temperature of the material in the evaporator reaches 65°C, the stirring is continued for 40 minutes. The material is pressed from the evaporator into the crystallization kettle with compressed air.

[0108] Slowly introduce chilled brine into the jacket of the crystallization kettle and cool it down to below 5°C at a rate of 5-10°C / 5 minutes. When the temperature of the crystallization kettle reaches 20°C, add a small amount of 2-imidazolidinone seed crystals into the crystallization kettle.

[0109] 4. Centrifugation and drying

[0110] The timing starts from when the temperature of the crystallization kettle drops below 5°C. After 30 minutes, the materials in the crystallization kettle are placed in a centrifuge for centrifugation. The centrifugal liquid is recycled and the solid materials are sent to a disc dryer for drying to obtain 131.18 kg of white crystals. The melting point of the product is analyzed to be 131.7°C, the product content is 99.26%, and the calculated product yield is 91.76%.

[0111] Example 3

[0112] 1. Cyclization reaction

[0113] 55Kg of softened water, 0.19Kg of catalyst triethylmethylammonium chloride, 0.22Kg of sulfonamide acid, 0.22Kg of sodium m-nitrobenzenesulfonate, 100Kg of urea and 106Kg of ethylenediamine were added to the reactor in sequence, and the mixture was sealed. The vacuum pump was turned on. When the vacuum degree of the reactor reached 0.045MPa, the reactor was maintained for 15 minutes. The vacuum pump was turned off. A stirrer was turned on and nitrogen was charged into the reactor. When the pressure inside the reactor reached 0.4, nitrogen was stopped from entering.

[0114] A heating medium was introduced into the jacket of the reactor, and the temperature was raised to 150°C within 35 minutes, and maintained at this temperature for 80 minutes;

[0115] Close the heating medium inlet valve, slowly open the reactor vent valve, discharge the gas to the ammonia absorption tank, and when the pressure in the reactor drops to normal pressure (the pressure gauge shows 0), turn on the vacuum pump. When the vacuum degree in the reactor reaches 0.06MPa, open the heating medium inlet valve, raise the temperature to 165℃ within 40 minutes, and maintain at this temperature for 2 hours;

[0116] Close the heating medium inlet valve under vacuum conditions, release the heating medium in the jacket, and then introduce cooling medium into the reactor jacket. Start cooling;

[0117] When the kettle temperature is about to reach below 90°C, the filtrate obtained by centrifugation in Example 2 is metered into the kettle along the inner wall, and fresh 95% ethanol is added to 300 kg, and stirring is continued for 1.5 hours.

[0118] 2. Filtration and evaporation of ethanol

[0119] After the stirring of the material with 95% ethanol is completed, the material is pressed from the reactor into the evaporator with compressed air to filter out the solid matter and mechanical impurities therein;

[0120] Steam is introduced into the jacket of the evaporator to start heating, and the ethanol obtained by evaporation is continuously reused. Once white solid material is observed at the bottom of the evaporator and the gas phase temperature exceeds 78°C and shows a trend of continuing to rise, the steam valve is immediately closed.

[0121] 3. Secondary dissolution, cooling and crystallization

[0122] Cooling water was introduced into the jacket of the evaporator. When the temperature of the material in the evaporator dropped below 90°C, the recovered ethanol obtained by evaporation in Example 2 and fresh 95% ethanol were added to 250 kg along the inner wall of the evaporator. The stirring was started by jogging (to prevent the stirring motor from being burned) to ensure that the stirrer started and operated normally. The evaporator was heated. The time was counted when the material in the evaporator reached 65°C, and the stirring was continued for 30 minutes. The material was pressed from the evaporator into the crystallization kettle with compressed air.

[0123] Slowly introduce chilled brine into the jacket of the crystallization kettle and cool it down to below 5°C at a rate of 5-10°C / 5 minutes. When the temperature of the crystallization kettle reaches 25°C, add a small amount of 2-imidazolidinone seed crystals into the crystallization kettle.

[0124] 4. Centrifugation and drying

[0125] The timing starts from when the temperature of the crystallization kettle drops below 5°C. After 20 minutes, the materials in the crystallization kettle are placed in a centrifuge for centrifugation. The centrifugal liquid is recycled and the solid materials are sent to a disc dryer for drying to obtain 142.26 kg of white crystals. The melting point of the product is analyzed to be 132.0°C, the product content is 99.51%, and the calculated product yield is 99.76%.

[0126] Example 4

[0127] 1. Cyclization reaction

[0128] 54Kg of softened water, 0.21Kg of catalyst triethylmethylammonium chloride, 0.24Kg of sulfonamide acid, 0.25Kg of sodium m-nitrobenzenesulfonate, 100Kg of urea and 108Kg of ethylenediamine were added to the reactor in sequence, and the mixture was sealed. The vacuum pump was turned on. When the vacuum degree of the reactor reached 0.06MPa, the reactor was maintained for 10 minutes. The vacuum pump was turned off. A stirrer was turned on and nitrogen was charged into the reactor. When the pressure inside the reactor reached 0.4, nitrogen was stopped from being introduced.

[0129] A heating medium was introduced into the jacket of the reactor, and the temperature was raised to 140°C within 40 minutes, and maintained at this temperature for 1.5 hours;

[0130] Close the heating medium inlet valve, slowly open the reactor vent valve, discharge the gas to the ammonia absorption tank, and when the pressure in the reactor drops to normal pressure (the pressure gauge shows 0), turn on the vacuum pump. When the vacuum degree in the reactor reaches 0.08MPa, open the heating medium inlet valve, raise the temperature to 155℃ within 50 minutes, and maintain at this temperature for 2 hours;

[0131] Close the heating medium inlet valve under vacuum conditions, release the heating medium in the jacket, and then introduce cooling medium into the reactor jacket. Start cooling;

[0132] When the kettle temperature is about to reach below 90°C, the filtrate obtained by centrifugation in Example 3 is metered into the kettle along the inner wall, and fresh 95% ethanol is added to 310 kg, and stirring is continued for 1.2 hours.

[0133] 2. Filtration and evaporation of ethanol

[0134] After the stirring of the material with 95% ethanol is completed, the material is pressed from the reactor into the evaporator with compressed air to filter out the solid matter and mechanical impurities therein;

[0135] Steam is introduced into the jacket of the evaporator to start heating, and the ethanol obtained by evaporation is continuously reused. Once white solid material is observed at the bottom of the evaporator and the gas phase temperature exceeds 78°C and shows a trend of continuing to rise, the steam valve is immediately closed.

[0136] 3. Secondary dissolution, cooling and crystallization

[0137] Cooling water is introduced into the jacket of the evaporator. When the temperature of the material in the evaporator drops below 90°C, the recovered ethanol obtained by evaporation in Example 3 is added and fresh 95% ethanol is added to 220 kg. The stirring is started along the inner wall of the evaporator (to prevent the stirring motor from being burned). Ensure that the stirrer starts and runs normally, heat the evaporator, and start the time when the material in the evaporator reaches 70°C. Continue stirring for 35 minutes. Use compressed air to press the material from the evaporator into the crystallization kettle.

[0138] Slowly introduce chilled brine into the jacket of the crystallization kettle and cool it down to below 5° C. at a rate of 5-10° C. / 5 minutes. When the temperature of the crystallization kettle reaches 22° C., add a small amount of 2-imidazolidinone seed crystals into the crystallization kettle.

[0139] 4. Centrifugation and drying

[0140] The timing starts from when the temperature of the crystallization kettle drops below 5°C. After 30 minutes, the materials in the crystallization kettle are placed in a centrifuge for centrifugation. The centrifugal liquid is recycled and the solid materials are sent to a disc dryer for drying to obtain 141.24 kg of white crystals. The melting point of the product is analyzed to be 131.7°C, the product content is 99.62%, and the calculated product yield is 99.15%.

[0141] Example 5

[0142] 1. Cyclization reaction

[0143] 52Kg of softened water, 0.18Kg of catalyst triethylmethylammonium chloride, 0.25Kg of sulfonamide acid, 0.23Kg of sodium m-nitrobenzenesulfonate, 100Kg of urea and 109Kg of ethylenediamine were added to the reactor in sequence, and the mixture was sealed. The vacuum pump was turned on. When the vacuum degree of the reactor reached 0.05MPa, the reactor was maintained for 15 minutes. The vacuum pump was turned off. A stirrer was turned on and nitrogen was charged into the reactor. When the pressure in the reactor reached 0.4MPa, nitrogen was stopped from entering.

[0144] A heating medium was introduced into the jacket of the reactor, and the temperature was raised to 145°C within 45 minutes, and maintained at this temperature for 1.3 hours;

[0145] Close the heating medium inlet valve, slowly open the reactor vent valve, discharge the gas to the ammonia absorption tank, and when the pressure in the reactor drops to normal pressure (the pressure gauge shows 0), turn on the vacuum pump. When the vacuum degree in the reactor reaches 0.06MPa, open the heating medium inlet valve, raise the temperature to 150°C within 50 minutes, and maintain at this temperature for 2.5 hours;

[0146] Close the heating medium inlet valve under vacuum conditions, release the heating medium in the jacket, and then introduce cooling medium into the reactor jacket. Start cooling;

[0147] When the kettle temperature is about to reach below 90°C, the filtrate obtained by centrifugation in Example 4 is metered into the kettle along the inner wall, and fresh 95% ethanol is added to 330 kg, and stirring is continued for 1 hour.

[0148] 2. Filtration and evaporation of ethanol

[0149] After the stirring of the material with 95% ethanol is completed, the material is pressed from the reactor into the evaporator with compressed air to filter out the solid matter and mechanical impurities therein;

[0150] Steam is introduced into the jacket of the evaporator to start heating, and the ethanol obtained by evaporation is continuously reused. Once white solid material is observed at the bottom of the evaporator and the gas phase temperature exceeds 78°C and shows a trend of continuing to rise, the steam valve is immediately closed.

[0151] 3. Secondary dissolution, cooling and crystallization

[0152] Cooling water was introduced into the jacket of the evaporator. When the temperature of the material in the evaporator dropped below 90°C, the recovered ethanol obtained by evaporation in Example 4 and fresh 95% ethanol were added to 220 kg along the inner wall of the evaporator. The stirring was started by jogging (to prevent the stirring motor from being burned) to ensure that the stirrer started and operated normally. The evaporator was heated. The time was counted when the material in the evaporator reached 65°C, and the stirring was continued for 30 minutes. The material was pressed from the evaporator into the crystallization kettle with compressed air.

[0153] Slowly introduce chilled brine into the jacket of the crystallization kettle and cool it down to below 5°C at a rate of 5-10°C / 5 minutes. When the temperature of the crystallization kettle reaches 20°C, add a small amount of 2-imidazolidinone seed crystals into the crystallization kettle.

[0154] 4. Centrifugation and drying

[0155] The timer starts when the temperature of the crystallization kettle drops below 5°C. After 25 minutes, the material in the crystallization kettle is placed in a centrifuge for centrifugation. The centrifuge liquid is recycled and the solid material is sent to a tray dryer for drying to obtain 141.56 kg of white crystals. The melting point of the product is analyzed to be 132.2°C, the product content is 99.43%, and the calculated product yield is 99.19%. The product analysis spectrum is as follows Figure 2 shown.

[0156] The results of the full analysis of Example 5 are shown in Table 1

[0157] Table 1 Product analysis results obtained in Example 5

[0158]

[0159] Product industry standard: T / ZZB 1581-2020 2-Imidazolidinone

[0160] Example 6

[0161] 1. Cyclization reaction

[0162] 55Kg of softened water, 0.17Kg of catalyst triethylmethylammonium chloride, 0.21Kg of sulfonamide acid, 0.24Kg of sodium m-nitrobenzenesulfonate, 100Kg of urea and 107Kg of ethylenediamine were added into the reactor successively, and the mixture was sealed. The vacuum pump was turned on. When the vacuum degree of the reactor reached 0.05MPa, the reaction was maintained for 20 minutes. The vacuum pump was turned off. A stirrer was turned on and nitrogen was charged into the reactor. When the pressure inside the reactor reached 0.35MPa, nitrogen was stopped from entering.

[0163] A heating medium was introduced into the jacket of the reactor, and the temperature was raised to 145°C within 40 minutes, and maintained at this temperature for 1.5 hours;

[0164] Close the heating medium inlet valve, slowly open the reactor vent valve, discharge the gas to the ammonia absorption tank, and when the pressure in the reactor drops to normal pressure (the pressure gauge shows 0), turn on the vacuum pump. When the vacuum degree in the reactor reaches 0.07MPa, open the heating medium inlet valve, raise the temperature to 160℃ within 50 minutes, and maintain at this temperature for 2.2 hours;

[0165] Close the heating medium inlet valve under vacuum conditions, release the heating medium in the jacket, and then introduce cooling medium into the reactor jacket. Start cooling;

[0166] When the kettle temperature is about to reach below 90°C, the filtrate obtained by centrifugation in Example 5 is metered into the kettle along the inner wall, and fresh 95% ethanol is added to 300 kg, and stirring is continued for 1 hour.

[0167] 2. Filtration and evaporation of ethanol

[0168] After the stirring of the material with 95% ethanol is completed, the material is pressed from the reactor into the evaporator with compressed air to filter out the solid matter and mechanical impurities therein;

[0169] Steam is introduced into the jacket of the evaporator to start heating, and the ethanol obtained by evaporation is continuously reused. Once white solid material is observed at the bottom of the evaporator and the gas phase temperature exceeds 78°C and shows a trend of continuing to rise, the steam valve is immediately closed.

[0170] 3. Secondary dissolution, cooling and crystallization

[0171] Cooling water was introduced into the jacket of the evaporator. When the temperature of the material in the evaporator dropped below 90°C, the recovered ethanol obtained by evaporation in Example 5 and fresh 95% ethanol were added to 240 kg along the inner wall of the evaporator. The stirring was started by jogging (to prevent the stirring motor from being burned) to ensure that the stirrer started and operated normally. The evaporator was heated. The time was counted when the material in the evaporator reached 65°C, and the stirring was continued for 30 minutes. The material was pressed from the evaporator into the crystallization kettle with compressed air.

[0172] Slowly introduce chilled brine into the jacket of the crystallization kettle and cool it down to below 5°C at a rate of 5-10°C / 5 minutes. When the temperature of the crystallization kettle reaches 25°C, add a small amount of 2-imidazolidinone seed crystals into the crystallization kettle.

[0173] 4. Centrifugation and drying

[0174] The timing starts from when the temperature of the crystallization kettle drops below 5°C. After 20 minutes, the materials in the crystallization kettle are placed in a centrifuge for centrifugation. The centrifugal liquid is recycled and the solid materials are sent to a disc dryer for drying to obtain 141.06 kg of white crystals. The melting point of the product is analyzed to be 131.9°C, the product content is 99.16%, and the calculated product yield is 98.87%.

[0175] Analyzing Example 1 and Example 2, the ethanol used was fresh ethanol instead of evaporation-recycled ethanol or centrifugation mother liquor, so the yield was slightly lower than that of the subsequent Example 3 using evaporation-recycled ethanol and centrifugation mother liquor.

[0176] Embodiment 3 to embodiment 6 are analyzed. Embodiment 3 to embodiment 6 all use the ethanol and centrifugal mother liquor evaporated and reused in the previous embodiment. Since the centrifugal mother liquor is a saturated ethanol solution of 2-imidazolidinone, once the ethanol is evaporated after adding the post-treatment system, it will precipitate from the system. Therefore, the product yield of embodiment 3 to embodiment 6 is relatively high and the purity is also relatively high. At the same time, it is also seen that with the increase in the number of times of recycling ethanol, the yield and purity of 2-imidazolidinone are relatively high, but still show a downward trend. It is also found in the study that the centrifugal mother liquor obtained in embodiment 6 is brownish yellow (the centrifugal liquid obtained by the first few batches of application is light yellow to yellow), which indicates that the impurities obtained by the reaction of 2-imidazolidinone are also precipitated one after another as the number of applications increases.

[0177] Comparative Example 1 was prepared without using any catalyst

[0178] The raw material ratio and process parameters used in Example 2 are completely consistent, except that no catalyst is used. The results are as follows: 122.23 kg of off-white fine particles are obtained after drying, the melting point of the product is analyzed to be 126.9°C, the product content is 97.15%, and the calculated product yield is 83.68%. This shows that if the catalyst is not used, the product yield is very low. The present invention reduces the reaction temperature and shortens the reaction time by using a catalyst. Although the product content reaches 97.15% without using a catalyst, the final product yield is low due to incomplete reaction under the set conditions.

[0179] Comparative Example 2 was prepared without using any catalyst and the reaction time was prolonged.

[0180] The raw material ratio and process parameters used in Example 2 are completely consistent, and no catalyst is used. The difference is that the reaction time of the low-pressure stage and the vacuum reaction stage is extended by one hour. The results are as follows: 122.37Kg of off-white fine particles are obtained after drying, the melting point of the product is analyzed to be 129.6°C, the product content is 98.30%, and the calculated product yield is 84.77%. This shows that if the catalyst is not used, the product yield is very low. The present invention reduces the reaction temperature and shortens the reaction time by using a catalyst. Although the product content reaches 97.15% without using a catalyst, the final yield of the product is low due to incomplete reaction under the set conditions.

[0181] Compared with Comparative Example 1, Comparative Example 2 does not use a catalyst. Although Comparative Example 2 prolongs the reaction time, the product yield and purity are not significantly improved.

[0182] From the spectrum of the product prepared in Comparative Example 2, it can be seen that there are many impurity peaks before the main peak, such as Figure 3 shown.

[0183] The results of the full analysis of Comparative Example 2 are shown in Table 2:

[0184] Table 2 Product analysis results obtained in Comparative Example 2

[0185]

[0186] Product industry standard: T / ZZB 1581-2020 2-Imidazolidinone.

[0187] Comparative Example 3, using a catalyst sulfonamide acid

[0188] The other operating conditions are the same as those in Example 2, except that only one catalyst, sulfonamide acid, is added, and the other two catalysts are not added. The amount of sulfonamide acid added is exactly the same as the amount of feed in Example 2.

[0189] The preparation results are: 1130.11 kg of white crystals were obtained, the melting point of the product was 131.5°C, the product content was 99.13%, and the calculated product yield was 90.89%.

[0190] Comparative Example 4: using two catalysts: triethylmethylammonium chloride 0.16 kg and sulfonamide acid 0.1 kg

[0191] The other operating conditions are the same as those in Example 2, except that only two catalysts, triethylmethylammonium chloride and sulfonamide acid, are added, and sodium m-nitrobenzenesulfonate is not added. The amounts of triethylmethylammonium chloride and sulfonamide acid added are exactly the same as those in Example 2.

[0192] The preparation results are: 131.87 kg of white crystals were obtained, the melting point of the product was analyzed to be 131.2° C., the product was 99.19%, and the calculated product yield was 91.25%.

[0193] Comparative Example 5 uses two catalysts triethylmethylammonium chloride and sodium m-nitrobenzene sulfonate

[0194] The other operating conditions are the same as those in Example 2, except that only two catalysts, triethylmethylammonium chloride and sodium m-nitrobenzenesulfonate, are added, and sulfonamide acid is not added. The amounts of triethylmethylammonium chloride and sodium m-nitrobenzenesulfonate added are exactly the same as those in Example 2.

[0195] The preparation result is: 131.88 kg of off-white crystalline powder is obtained, the melting point of the product is 135.7° C., the product content is 86.22%, and the calculated product yield is 80.13%.

[0196] Analysis of Comparative Examples 3 to 5 shows that sulfonamide acid is the main catalyst, triethylmethylammonium chloride and sodium m-nitrobenzenesulfonate are auxiliary catalysts when participating in the reaction. The yield and purity of the obtained products are similar when sulfonamide acid is used alone, or when sulfonamide acid and triethylmethylammonium chloride are used in combination, or when sulfonamide acid and sodium m-nitrobenzenesulfonate are used in combination. However, when only triethylmethylammonium chloride and sodium m-nitrobenzenesulfonate are used in combination, the product appearance is poor and the quality indicators are unqualified, indicating that the use of only triethylmethylammonium chloride and sodium m-nitrobenzenesulfonate has little catalytic effect on urea and diethylamine.

[0197] Comparative Example 6: The catalyst zinc oxide (ZnO) disclosed in the prior art is used.

[0198] The other operating conditions are the same as those in Example 2, except that a catalyst zinc oxide (ZnO) is added in an amount of 0.5 kg. None of the three catalysts used in the present invention, triethylmethylammonium chloride, sodium m-nitrobenzenesulfonate, and sulfonamide acid, is added.

[0199] The result is: 103 kg of off-white powder was obtained, the melting point of the product was 155.7° C., the product content was 74.83%, and the calculated product yield was 54.30%.

[0200] Analysis: According to the product test results, the melting point of the product is 155.7°C, which is far higher than the product standard (T / ZZB 1581-2020 2-imidazolidinone), and the content is also unqualified, so the product is judged to be unqualified. The key factor is that the use of the catalyst zinc oxide (Zn0) disclosed in the prior art is carried out under anhydrous conditions and a reaction temperature of 200°C. Using the process conditions of the present invention, the reaction temperature is only about 160°C, and the reaction is incomplete; and the catalyst zinc oxide (Zn0) is used as a catalyst for the reaction, and the three catalysts used in the present invention, triethylmethylammonium chloride, sodium m-nitrobenzene sulfonate, and sulfonamide acid are reacted. The reaction conditions, reaction process operating parameters, and reaction mechanisms are different. The process parameters of the present invention are not suitable for production using zinc oxide (Zn0), so the prepared product is unqualified.

[0201] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A production process for high-purity 2-imidazolidinone, characterized in that: include: Urea and ethylenediamine are used as raw materials, and a two-step reaction of low-pressure reaction and vacuum reaction is carried out in the presence of a catalyst and water. After the reaction is completed, the reaction liquid is cooled and then post-processed; the catalyst is a combination of triethylmethylammonium chloride, sulfonamide acid and sodium m-nitrobenzene sulfonate; the vacuum degree of the low-pressure reaction is 0.3-0.4MPa, and the reaction temperature is 140-150°C; the vacuum degree of the vacuum reaction is 0.06-0.08MPa, and the reaction temperature is 155-165°C.

2. The production process of high-purity 2-imidazolidinone according to claim 1, characterized in that: The post-processing step includes filtering and evaporating ethanol; further, the post-processing step also includes adding ethanol for secondary dissolution, followed by secondary cooling, crystallization, centrifugation and drying.

3. The production process of high-purity 2-imidazolidinone according to claim 1, characterized in that: The molar ratio of urea, ethylenediamine and water is 1:1.03-1.09:1.68-1.

85.

4. The production process of high-purity 2-imidazolidinone according to claim 1, characterized in that: The amount of triethylmethylammonium chloride added is 0.13%-0.22% of the urea mass.

5. The production process of high-purity 2-imidazolidinone according to claim 1, characterized in that: The amount of sulfonamide acid added is 0.05%-0.25% of the urea mass.

6. The production process of high-purity 2-imidazolidinone according to claim 1, characterized in that: The amount of sodium m-nitrobenzene sulfonate added is 0.16%-0.25% of the urea mass.

7. The production process of high-purity 2-imidazolidinone according to claim 1, characterized in that: The production process comprises the following steps: S1. Cyclization reaction: Add the measured water, catalyst, urea and ethylenediamine to the reactor in sequence, seal it, turn on the vacuum pump, and when the vacuum degree of the reactor reaches 0.04-0.06MPa, maintain it for 10-20 minutes, turn off the vacuum pump, turn on the agitator, and fill the reactor with nitrogen. When the pressure in the reactor reaches 0.3-0.4MPa, stop the nitrogen introduction; Pass the heating medium into the jacket of the reactor, raise the temperature to 140-150°C within 30-40 minutes, and maintain this temperature for 1-1.5 hours; Close the heating medium inlet valve, slowly open the reactor vent valve, discharge the gas into the ammonia absorption tank, and when the pressure in the reactor drops to normal pressure, turn on the vacuum pump. When the vacuum degree in the reactor reaches 0.06-0.08MPa, open the heating medium inlet valve, raise the temperature to 155-165℃ within 40-50 minutes, and maintain at this temperature for 2-2.5 hours.

8. The production process of high-purity 2-imidazolidinone according to claim 7, characterized in that: Post-processing includes: Under vacuum conditions, close the heating medium inlet valve, release the heating medium in the jacket, and then introduce cooling medium into the jacket of the reactor to start cooling; When the kettle temperature is about to drop below 80°C, 95% ethanol is metered into the reaction kettle along the inner wall, and stirring is continued for 1-2 hours.

9. The production process of high-purity 2-imidazolidinone according to claim 8, characterized in that: Post-processing also includes: S2, filtration, evaporation of ethanol: After the material with 95% ethanol is added and stirred, compressed air is used to press the material from the discharge port of the reactor into the evaporator through the pipeline filter installed on the pipeline connected to the evaporator to filter out solid matter and mechanical impurities; Steam is introduced into the jacket of the evaporator to start heating. The ethanol obtained by evaporation is continuously reused. When white solid material is observed at the bottom of the evaporator and the gas phase temperature exceeds 78°C and shows a trend of continuing to rise, the steam valve is immediately closed; S3, secondary dissolution, cooling, crystallization: Cooling water is introduced into the jacket of the evaporator. When the temperature of the material in the evaporator drops below 90°C, the measured 95% ethanol is added along the inner wall of the evaporator. The stirring is started by jogging (to prevent the stirring motor from being burned) to ensure that the stirrer starts and runs normally. The evaporator is heated. The time is counted when the temperature of the material in the evaporator reaches 65-70°C. The stirring is continued for 20-40 minutes. The material is pressed into the crystallization kettle from the discharge port of the evaporator through the pipeline filter installed on the pipeline connected to the crystallization kettle by compressed air; Slowly introduce chilled brine into the jacket of the crystallization kettle and cool it down to below 5°C at a rate of 5-10°C / 5 minutes; when the temperature of the crystallization kettle reaches 20-25°C, add a small amount of 2-imidazolidinone seed crystals into the crystallization kettle; S4, centrifugation, drying: The timer starts from the time when the temperature of the crystallization kettle drops below 5°C. After 20-30 minutes, the material in the crystallization kettle is placed in a centrifuge for centrifugation, and the solid material is sent to a disc dryer for drying; the centrifuge liquid is reused.

10. The production process of high-purity 2-imidazolidinone according to claim 9, characterized in that: In the post-treatment step, 95% ethanol is added twice, and the mass ratio of 95% ethanol to urea is 1:5.3-6.0.

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